Smartwool PhD Outdoor Ultra Light Micro Sock
SmartwoolPhD Outdoor Ultra Light Micro Sock

Get your degree.

Unless you're an anomaly, your feet will sweat during activity, so the SmartWool PhD Outdoor Ultra Light Micro Sock is designed to breathe and offer cooling, quick-drying comfort no matter how rigorous your favorite outdoor activity can get. A 4-degree Elite Fit system uses two elastics for greater stretch and recovery, keeping this sock in place, while the patented ReliaWool technology in high-impact areas improves durability and support. Plus, moisture-managaing properties pull sweat away from your skin to prevent the dreaded swampfoot.

  • Lightweight, breathable sock for cool comfort on trail runs
  • Moisture-wicking properties deliver dry comfort
  • Stretchy design ensures the sock stays in place
  • High-impact areas provide stronger durability
  • Reviews
  • Q & A

Learn More: Smartwool PhD Socks

Learn more about the comfort, fit, and durability of Smartwool PhD performance socks. #gofarfeelgood

Exactly what I needed!

  • Familiarity: I've used it several times

Was looking for a slim, lightweight sock, yet still with wool and this sock met every need. Fits perfectly, heel to toe. Seems like this sock will go a long way.


  • Familiarity: I've put it through the wringer

I have had a few pairs of the phd socks over the years, but the current version has highest quality construction. Unlike previous versions this iteration has the seams in better locations for a more durable feel. I have had other phd socks rip but this one seems like it will last for years to come. Breathable and soft, smart wool really knows their socks!


  • Familiarity: I gave it as a gift but have feedback to share
  • Fit: True to size
  • Size Bought: XL

First of all, you absolutely cannot go wrong with SmartWool socks of any style. These are exactly as described. They are on the thinner side of SmartWool's line of socks, but that is exactly what I wanted.

summer option

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: True to size

Bought these for my summer days. I have thicker ones for winter. The material is excellent and feel great on your foot. They are lighter so I haven't worn them in the colder winter days yet.